Field of the Invention
The present invention relates to a method for connecting at least two components of an endoscope or medical instrument, to a component of an endoscope that is designed for connecting to at least one further component of the endoscope by means of high-temperature brazing and for this purpose has a joining region, and to an endoscope with an endoscope head, which has a housing and at least one built-in part and/or at least one built-on part.
Description of the Background Art
Endoscopes are used for many applications in medicine and technology. An endoscope typically comprises an elongate shank, which is suitable for inserting into a cavity, for instance into a cavity inside the body or a cavity in a technical article, and in the distal end region of which, i.e. remote from the user, there is arranged an endoscope objective lens for producing an endoscopic image of an object field located in the cavity. The shank may be of a rigid, semirigid or flexible design. The recorded endoscopic image is typically passed on to the proximal end of the endoscope, i.e. near the user, by way of an image retransmitter arranged within the shank. Known to act as image retransmitters are in particular lens systems, which may comprise a plurality of rod lenses, and ordered bundles of optical fibers. Since sufficient light is not generally available in the cavity, a light guiding system having optical fibers is also usually arranged within the shank of the endoscope, in order to transport light to the distal end of the endoscope for illuminating the object field. Furthermore, the shank may have one or more working channels for leading through endoscopic working instruments, with which manipulations can be carried out within the cavity. Also often provided within the shank are flushing, suction and insufflation channels, with which liquids or gases can be transported into the cavity and out from it during endoscopic operations.
Generally arranged at the proximal end of the shank is an endoscope head, which remains outside the cavity during the use of the endoscope. The endoscope head has a housing and a plurality of built-in parts and built-on parts. In particular, the endoscope head is adjoined on the distal side by the shank of the endoscope, on the proximal side by an eyepiece cup or a connection for an endoscopic video camera, and on the side of the endoscope head there is a connection for connecting a fiber optic cable, with which the illuminating light can be supplied from an external light source. Furthermore, the endoscope head may have flushing, suction and insufflation connections and also inlets of working channels, through which endoscopic working instruments can be inserted, as well as guides for the channels and optical elements arranged within the endoscope head. Typically, at least the housing of the endoscope head can be formed of high-grade steel.
During the use and the preparation of an endoscope, it is exposed to considerable mechanical, thermal and chemical loads. In particular, vibrations may act on the endoscope, considerable forces may be exerted on the connections during use, and the endoscope is exposed to chemically aggressive media and to increased pressure and increased temperature during cleaning and sterilization. It is therefore necessary to connect the built-in parts and built-on parts to the housing of the endoscope and to one another securely and reliably and in a sealed and thermally stable manner.
For this purpose it is known to connect the components of the endoscope head to one another by laser welding. However, the melting of the material during the laser welding has the effect of weakening the component concerned in the region of the welded connection, which in particular in the case of thin-walled components, which are used in the case of endoscopes with a small shank diameter, impairs the strength. In addition, laser welding does not always successfully produce a fluid-tight connection, in particular in the case of relatively long weld seams. To increase the strength and to ensure the seal-tightness of a laser-welded connection, it is often additionally secured by adhesion. Since in the production of an endoscope or an endoscope head a plurality of connections have to be created between components, which moreover are often arranged within the housing of the endoscope head, and are therefore only poorly accessible, a large number of successive production steps are necessary, which further increases the production costs.
US 2005/0077343 A1 discloses a method for brazing two or more high-grade steel components of a medical endoscope, wherein one component is connected to another by means of a brazing solder material that contains at least 62.5% by weight of gold. In this case, the components are subjected in a first step to a heat treatment at a temperature of 1050 to 1200° C. in a hydrogen-containing atmosphere or in a vacuum. In a second step, one of the components may form a gap with the other, and in a third step the brazing solder material is fed to the gap in a molten state in order to connect the components to one another. For feeding in the brazing solder material, it may be wound as a wire around a tube to be brazed in, for example, or else be applied as a paste in the region of the connection. However, this known method is not optimal in terms of costs and suitability for use, in particular in the production of an endoscope head.